Circuit breaker control system



Patented Sept. 18, 1945 UNITE-"D VKSTATES PAT ENT OF F I C E 2,385,042 CIRCUIT BREKER CONTROL SYSTM William R. Taliaferro,rEdgewood,'Pa., assgnor to Westinghouse 'Electric Corporation, vEast Pittsburgh, Pa., a corporation V(if Pennsylvania Apucation April 23, 1943, seria1Nof4841v7e 5 Claims.

My invention relates, generally, to circuit breaker control systems and has reference in particular to automatic reclosing circuit breaker systems or'sectionalizers for feeders for stub or multiple feed operation. u 1 Y Generally stated, it is .anobject Aof my invention tov provide for automatically reclosingthe circultbreakerof a sectionalizing feeder ina mannerthat is saferas well'as simple and inex pensive regardless of whether the feeder is op-v erating as astubor multiplef eeder. y More s pecii'lcally, itj is anobject of my inveny tion to provide for selectively and automatically controlling the connection ofthe automatic reclosing appara-tus for the circuit breaker to one yside or another. ofthe circuit breaker in aseotionalizing feederl which may be arrangedto operate in either stub (resistance measuring)l or multiple (voltage measuring) feed, depending upon which side ofthe feeder is toY have its load conditions measured.A

It is also an object of my invention to provide for automatically changing the connections of a recalibrating relay in an automatic vreclosing circuit'breaker system fora sectionalizing feeder which may lfeed in either direction, in either stub or multiple feed, so that itl will befconnected-to the feeder on one side o f thecircuit"breaker,v or the other, for measuringthe load conditions thereof to determine whether ornot the circuit breaker mayA be closed without-.exceedingthe maximum safe current capacityofthe system. A further object of,V myi invention is to provide, first, for determiningwhich ofthe two sections of a sectionajlizing feeder onopposite. sides of a circuit breaker is operating under substantially normal conditions, and which requires to have its rload conditions measured, and `then provide for Calibrating a-.load measuring device of the circuit breaker c-ontrol system inv accordance With either the loadlresistance or the voltage of ythe section l to ybe-Ineasuredfor Operating in stub or multiple feed-before determiningwhen the circuit breaker may-be closed safely. n Other objects,r wilLin parl?, be obvious, and will; inv part, beexplained hereinafter.

Directrucurrent feeders `of the usual typefor feeding electrical energy/in one direction only have been heretofore provided with automatic reclosing equipmentzfor operation on stub (resls'tanoermeasuring): and vmultiple (voltage measuringl feed reclosing; or for'operati'on on either stub or multiplefeedwith automatic recalibration-for either condition. Sectionalizing feeders diil'er from the ordinaryfeedrsin that they: are

usually arrangedto be energized from both ends for supplyinga plurality of; loads at either or both endsi Under these conditions, reclosing of the feeder breaker must be effected under a nurnber of different conditions, depending upon both the direction in which the feeder is to supply energy, yand whether or not the feeder is operating in stub o r multiple feed. Since sectionalizing feeders are arranged to be fed from bothends the automatic reclosing circuit breaker apparatus is usually calibrated for recloslng on a multiple feed or voltage measuring basis. By changing the value of the resistance in the Ameasuring circuit, the automatic reclosing circuit breaker apparatus can be calibrated to close on a stub feed basis. l` Thus calibrated, however, it would be entirely unsuitable for. operation if the feeder isalso to operate-at*` times on multiple feed.

Heretofore, automatic reclosingcircuit breaker apparatus has been provided with measuring equipment calibrated for stub feedreclosing, and in addition a voltage relaytov measure thevoltage difference across the circuit breaker contacts for operating on multiple feed. Such a system operates satisfactorily only: Whenthe'voltageconditions are limited torelativelyhighvoltages on the side of the feeder having the vlowest voltage. Excessvely low voltages prevent the voltage difference relays from operating, which is correct,

'but this does notvprevent the stub feedmeasuring equipmentV from functioning to close the breaker. Eveny though the voltage is very low, the feeder is still a multiple feede'nand yet the automatic reclosing circuit breakerapparatus is measuring as a stubv feeder, which results in incorrect measuring, permitting the feeder to be closed under faultconditions or on excessive loads Whichresult inretripping of the breaker and .pumping thereof.

. In practicing .my invention, the closureof the circuit breakerin a sectionalizing feeder,-,whi`ch maybe connected for feeding .power in either direction, in eitherstubf or multiple feed,i s controlled. ink the rst instance by determining through the medium of a. selective control relay which section of the feeder isnormally energized and which section is to have its load conditions measured. The recalibrating relay which changes; the connections of theload measuring relay for vstub or multiple'feedV is then connected to thesection ofthe feeder which is to have its load conditions measured. lThe-load conditions vof this section may then be readilymeasured by Ithe load `measuring relay to determine, Whether the effective load resistance of the section is sufficiently high to limit the load current to a safe value, if this section of the feeder is operating in stub feed, or if its voltage is sufficiently high to limit the load current if it is operating in multiple feed.

For a more complete understanding of the nature and scope of my invention, reference may be had to the accompanying drawing in which the single figure is a diagrammatic view of an automatic reclosing circuit breaker system for a sectionalizing feeder embodying the principal features of the invention.

Referring to the drawing, the :reference numeral l may denote generally, an automaticreclosing circuit breaker system for a sectionalizing feeder comprising adjacent feeder sections I I and I2 connected by a circuit breaker I3 and supplied with electrical energy from either or both ends from sources such as the generators I4 and I5, for supplying electrical energy to loads denoted generally, by the numerals I6 and I "I, An overload relay I8 having an operating winding I 9 may be provided for opening the circuit breaker I3 when the current exceeds a predetermined value, and control means denoted generally by the numeral may be provided for automatically reclosing the circuit breaker as soon as circuit conditions permit.

The circuit breaker I3 may be provided with main contact members I3a for connecting sections II and I2 of the sectionalizing feeder, auxiliary contact members, and an operating winding 2| for effecting closure of the contact members. Energization of the operating winding ZI may be controlled by an auxiliary breaker relay 23 having an operating winding 24.

In order to provide for determining whether or not the circuit breaker I3 may be reclosed to connect the adjoining sections II and I2 of the sectionalizing feeder without exceeding the maximum safe value of the current for which the system is designed, load measuring means 2E may be provided. The load measuring means may be of any suitable type such as, for example, a ret lay having a disk 2'I of aluminum or some other suitable non-magnetic material rotatably mounted on a shaft 28, and provided with ran insert 3i! of magnetic material, A movable contact arm 32 on the shaft 28 is arranged for engaging spaced` 'v stationary contact members 33 and 34. Operation of the relay may be effected by means of opposed operating windings 36 and 3'I which may be connected to the normal section of the feeder and the section which is to have its load conr ditions measured, respectively, to energize magnetic core members 38 and 39 which act on the magnetic insert 30, tending to rotate the disc 21 in opposite directions. A time delay action may be secured by utilizing a substantially C-shaped permanent magnet 40, having an air gap to receive the outer edge of the disc 2T, whereby a drag may be exerted to retard rotation of the disc. When the winding 36 is energized, the disc which Winding is arranged to be connected intermediate a load measuring resistor 44, arranged to be connected in bridged relation with the circuit breaker I3, through suitable control switches and 46. An auxiliary reclcsing relay 41 having an operating winding 48 may be provided for controlling the connection of the load measuring resistor 44 to section II, and the ccnnection of the operating winding 3T to the load measuring resistor in response to engagement of the contact arm 32 with the contact 33.

` With a view to recalibrating the load measuringr relay 26 for operation on either stub or multiple feed, a recalibrating relay 50 may be provided having an operating winding 5I. The recalibrating relay 50 may be arranged to vary the effective value of the recalibrating resistance, being, for example, connected in shunt relation with the recalibrating resistor 42 through contact members 561), for effectively inserting it in, or removing it from, the circuit of the operative winding 3T.

` In order to determine to which side of the circuit breaker I3 or to which section of the feeder the recalibrating relay 50 and the operating winding 36 of load measuring relay 26 should be connected, a selective control relay 53 may be provided, having an operating winding 54. The selectiVe control relay 53 may be provided with normally open contact members 53a for connectingY the operating winding 36 of the loa-d measuring relay to section II of the feeder under predetermined operating conditions, andnormally closed contact members 53h for ccnnectingthe operating winding 36 of the load measuring relay to section I2 under other operating conditions. Additional normally open contact members 53e may be provided for connecting the recalibrating rclay 5D to section I2 of the feeder under predetermined operating conditions, and normally closed contact members 53d may be provided for connecting the recalibrating relay 50 to section II of the feeder under other operating conditions.

` As soon as a fault occurs, the main contacts I3a of the circuit breaker I3 open upon deenergization of the operating winding ZI when the overload relay I8 opens its normally closed contact members I8a, interrupting the circuit through the operating winding 2I between the feeder and ground. As soon as the circuit breaker opens. the overload relay 8 returns to the deenergized position, completing an energizing circuit for the operating winding 54 of the selective control relay 53 from section II of the feeder, through control switch 45, positive control bus 56, operating winding 54, conductor 5l, contact members 41d of the auxiliary reclosing relay 4'I, contact members I3d of the circuit breaker, negative control bus 59 and contact members I8a of the overload relay I8, to ground.

If substantially normal voltage exists on section I I` the selective control relay 53 operates, otherwise it remains in the deenergized position. If it operates, contact members 53a and 53e close, and at the same time contact members 53bfand 53d open. lThe operating winding 36 of the load measuring relay 26 is thereby connected to secv'tion II of the feeder through the circuit extending from the section I I through control switch 45, positive control bus 56, contact members 53a of the selective control relay, control resistor 62, conductor 64, contact members |31) of the circuit breaker I3, control resistor 65, conductor 6l, operating winding 36, and negative control buses 68 and 69 to ground, or the other side of the line.

frorectin I 21,1 through control `switch 46,- 'con'- diictoi"1II,f contact' members53'c of! the selective contiolrel f control resistor 1I, conductor' 72, contact members-143e of" the'cirlcuit breakerA I3, operating winding'51, condiictor14fj contact mem- (resistance measiiriii'gl feed as shown, no`voltage isfalppliedftof thefoperatin'g winding 5It of therecalibia'tin'glrelay-l Accordingly, contact members met ienialri'jclosedi so thatrecalibrating resistor After'a predetermined time delay, Athe movable Contact' arm' 32'i engagesf the'y stationary contact member 33 to establish'an energizing circuit for the operating' Winding 48'of' theauxiliary reclosirig relay 4:12 This current extends from 'sectionA I-`I through' control 1 switch 4 5; :positive control v' bus 56? :contact: members 53a of the selective control' relay "58;=control resistor 62;'conductor 64, con'- ductorl 80;-v :controlY resistor A82, operating windingA 48-,^conductors"f 84` and 85,y movable contact armr njstaitionary contact member 33, and." :negative closing relay 41 operates, closing its contact mem-'- bers I'Imtoi-connectthe 'load-measuring Vresistor 44* to `se'ctioril band closingiitsr contact members b'to'fconne'ct the operating.' winding 31 of. the load m'easuringmeans` 26 tot-he loadmeasuringy resistor 44:-y

Ifftlieload characteristics oi? sectionA I2 are satis'ractory;v operating winding F31 causes -contact ate'r a predetermined timeldelay, to complete any control-relay 53 isv connected thereto upon the return tothe deenergizedposition ofthe overload relay flag. the relay 53 does not-operate but remains in the deenergized condition. Accordingly, the connections of the recalilbrating relay lSil are reversed'and the relayis' connected to section I I, instead of section I2, as hereinbefore described, through the normally closed contact members 53d and control switch 45. likewise, the operating winding 36 of the load measuring relay 26 is connected to section I2, through the normally closed members 53h and control switch 46, instead of to section II. The operating winding 31 of the load measuring relay is thereafter connected to the load measuring resistor 44 through contact members 41h of the auxiliary reclosing relay. The sequence of operation thereafter for stub feed, is substantially the same as hereinb'efore described, except in that section I2 is considered as the normal or supply conductor While section I I is considered as the stub or supplied conductor which is to have its load characteristics measured.

If, when the recalibrating relay 50 is connected t either section I2 or section I I, depending upon whicli'oflthesesections is the one -tozwhich power is"to'vbe:supplied,. a substantial voltage exists on. thisconductor, such'a's would bethe casewerepthe switchv 882 between theV generator I54 and section I2 r closed, this indicates thatithe load measuring;

relay 26`fmust'lbe caliblatedzfor operating on-multiple (voltagemeasuring) feed. Accordingly, the recalibrating relay 50 operates in response to the voltage-on the section, opening: contact members 56h. to'insert recalibrating resistor I42 inl series with the operating winding 31'of the loadfmeasuring relay 26 and providing a holding circuit for its operating Winding 5I, through the circuit eX- tending from section I I or I2 as the ease may be, through the control switch 45 or 46, positive controlbus 56 or conductor 18, contact members 53d o-r 53e, control resistor 1I, conductor 12, contact members ISC, operating winding 5l, contact members 50a and negative control bus 59 t0 ground.

The load measuring relay 26 is thereby recalibrated for multiple-feed. When recalibrated, the operating winding 31`is so connected that the relay 26cannot operate to effect closure of the circuit breaker I3: until the voltage of section II or I2 of the feeder, as the case may be, has increased to a sufficiently high value whichwill not permit an excessive interchange of' current between sections I I\ and I2 after closure of circuit breaker I3.

From'the accompanying' drawing and the above description,.it is apparent that I have provided in a simple and effective manner, for controlling the operation of a circuit breaker in a sectionalizing feeder with the same desirable characteristics as are obtained in the case of an automatically recalibrated circuit breaker control for a standard feeder. Such recalibrating equipment isy of greatimportance under conditions which often exist in coal mine operations where a number of direct current generators are Voperated for supplying'genergy `to different points of the mine or mine trolley'system under the usual conditions,l

sov that the sectiona-lizing feeders operate in multiple feed, and'inv either directionv depending on load variations. During week-ends or no work periods,.all of the generators but one may be shut down, so that the sectionalizing feeders then operate invstub feed. Under this4 condition, unless the automatic reclosing apparatus of the sectionalizing feeders is recalibrated, it is impossible to reelose the feeders after a fault unless the load is. reduced to zero which is usually an impossible condition. By utilizing a system embodyingthe principal features of my invention, adequate protection is provided and prompt restoration of service is secured under all operating conditions.

Since certain changes may be made in the above description, and different embodiments may be made without departing from the scope or spirit thereof, it is intended that all of the matter contained in the above description, and shown in the accompanying drawing, shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. A control system for a circuit breaker disposed to provide a tie connection between a pair of feeder sections connecting a plurality of sources and loads for supplying electrical energy to the loads in either direction either in multiple or singly'comprising, a `control relay effective to determine which of the feeder sections is to have its load characteristics measured, load measuring means selectively connected to the section to have its load characteristics measured by the control means to determine whether the load characteristics of said section are such that the circuit breaker can be closed without exceeding a predetermined transfer of electrical energy from one section to another, means operable to recalibrate the load measuring means if the section is to have its load characteristics measured is being supplied from another source, circuit means including contacts of the control relay for selectively connecting the recalibrating means to whichever section is to have its load characteristics measured, and means operable in response to a predetermined operation of the load measuring means to eiect closure of the circuit breaker.

2. In a control system for a load measuring device Which is disposed to measure' either the potential or load resistance of either of a pair of sections of a sectionalizing feeder connected by a circuit breaker, a selective control relay energizable from one section of the feeder to determine which section is to be supplied With electrical energy and connect the load measuring device to the said one section when the said one section is at substantially normal voltage and to the other section when it is not at substantially normal voltage, a recalibrating resistor connected in circuit with the load measuring means, recalibrating means effective to control the eiective value of the recalibrating resistor and recalibrate the load measuring device when the section to be supplied with electrical energy is at a potential dueto the energization from another source, and circuit means including normally open contacts and normally closed contacts of the selective control relay for connecting the recalibrating means to the section to be supplied with electrical energy.

3. An automatic reclosing system for a sectionalizing feeder comprising adjoining sections connected by a circuit breaker and connected between a plurality of loads and sources for supplying electrical energy in either direction comprising, current responsive means to open the circuit breaker in response to a fault on either side of the circuit breaker, load measuring means disposed to be connected to the section supplying electrical energy and the section to be supplied with electrical energy in predetermined relation for determining whether the circuit breaker may be safely closed, selective control means connected to one of the sections operable to control the conr nections of the load measuring device to said one of the sections or to the other in accordance with the existence or non-existence of' substantially nonmal voltage on said one section, circuit means including a resistor having an intermediate point connected to recalibrating means disposed to be connected under the control of the selective control means to the section to be supplied, said re- Calibrating means being effective to vary the calibration of the load measuring means in accord ance with the existence or non-existence of potential on the section to be supplied with electrical energy, control means operable under the control of the load measuring means to connect the recalibrated load measuring means to the section to which power is to be supplied, and circuit means effective to close the circuit breaker under the control of the load measuring means.

4. The combination with a circuit breaker connecting adjoining feeder sections, fault responsive means for opening the circuit breaker, a load measuring device for determining the load characteristics of one of the sections, selective control means for determining in accordance with the existence or non-existence of substantially normal potential on one of the sections to which of the sections the load measuring device is to be connected, and auxiliary control means responsive to predetermined operation of the load measuring means to reclose the circuit breaker, of a recalibrating resistor connected in circuit relation with the load measuring means, recalibrating means controlling the effective value of the recalibrating resistor in accordance with whether 0r not a potential exists on the section to have its load characteristics measured, and circuit means including an impedance having a midpoint connected to the recalibrating means associated with the selective control means eiective to connect the recalibrating means to the section whose load characteristics are to be measured.

5. The combination in an automatic reclosing system for a circuit breaker connecting the sections of a sectionalizing feeder arranged to supply electrical energy in either direction to one or more loads from one or more sources, of impedence means bridging the circuit breaker, a load measuring device having one operating winding connected intermediate the bridging impedance and an opposing operation winding, selective control means disposed to be energized from one section of the sectionalizing feeder when said one section is at substantially normal voltage for connecting the opposing Winding to the section of the feeder to be supplied withenergy, recalibrating control means disposed to be connected to the section of the feeder to which energy is to be supplied under control of the selective control means, and means responsive to a predetermined operation of the recalibrating control means effective to recalibrate the load measuring device for measuring the voltage of the section to be supplied with energy.

WILLIAM R. TALIAFERRO. 

